Microsoft's RearType: Physical keys to the iPad, Kindle and tablet kingdoms?
zdnet.com
zdnet.com
They only had 12 participants, and while they cite 15 WPM as average performance, one of the participants did 47 WPM. Unfortunately, they don't give original keyboard speed of participants.
Their testing also compared between the 3 - touchscreen, keyboard, and rear-type in relatively short bursts. The all-important question is how well would someone do if they used this exclusively as their input device?
Judging from the pictures, the hardware used is a MIMO usb monitor[1] with an ergodex keyboard[2].
It shouldn't be a physical keyboard, but rather a touchpad on the back. With faux-translucency so you can see where your fingers are resting. By default, when you rest your four fingers to each side of the back... the keyboard home row adjusts to rest under your finger
The way it should work is that it detects a keypress when the user presses down and releases a key within half a second.
This would allow them to build a thin device, easily support landscape and portrait, and even provide multiple keyboard types.
Snark aside, you've never had an email you're writing ('short text entry') turn into something longer ('an essay')? At what point do you sit down?
Or how about a 30-minute long subway commute? No tables, and during rush-hour, no seats either. Or on bus or in a car? You can awkward perch a tablet on your lap in a pinch; no one is saying you can't still do that, but, well, it's awkward.
I think that both ideas have a snowball-in-hell chance of being in an actual product. A significant power of a touch interface is directness ( http://portal.acm.org/citation.cfm?id=1453235 ). Fingers on the back of the device break directness.
That's my dream portable computer.